1. Field of the Invention
The present invention is related to a ski boot whose shell base is overlaid with an upper having a front cuff and a rear spoiler which are connected to one another along at least one upper extension of the shell base, and is related to the means used for controlling the flexion of the upper with respect to the shell base with regard to force, position, and clearance amplitude.
2. Discussion of Background and Material Information
A known boot of this type is described in patent application DE 3247515. According to this patent application, the flexion control of the upper, which covers two lateral extensions that extend up to the fore-foot, is ensured by means of an elastic element interacting between the cuff or front cuff and the shell base, whereas the clearance amplitude is determined by means of a tenon fixed on the shell base which cooperates with a slot of the front cuff, concentric to the journal axis of the latter.
It is also provided that the tenon and the slot are capable of being adjusted in position on the shell base to fix especially the angular end position of the front cuff towards the rear as well as the advance angle. In such a ski boot, although the basic functions of the flexion control of the upper are ensured, it appears however, that some of them are poorly accomplished.
Indeed, it is noted that the tenon-slot means for limiting the clearance amplitude of the front cuff and for determining the rear end position of the latter are located on this side of its journal axis, in the vicinity of the sole, whereas the portion of the front cuff actuated by the lower part of the leg is a channel-shaped upper front portion, the farthest away from the journal axis.
Now, such an arrangement of the means, with respect to the journal axis of the front cuff, determines a large lever arm between the channel of the latter and said axis, and a small lever arm between the tenon and the axis.
Consequently, the forces applied on the channel-shaped portion are transmitted and substantially increased in the area of the tenon-slot limitation means which constitute the resistance to the force applied and which, a special arrangement excepted, are destined for substantial wear and tear, even for a rapid destruction.
Likewise, this substantial difference of the lever arms and the spacing of the resistance point with respect to the point of application of the force also generates elastic deformations, even the buckling of the sides of the front cuff from its frontward or rearward abutment position on the limitation means, and thus not provide firm abutments limiting flexion amplitude, whereas these abutments are meant to determine the stiffness of the upper towards the front, and to determine the quality of the reclaiming of rear support towards the rear.
Moreover, since the described clearance amplitude limitation means of the front cuff are not mutually adjustable, it is not possible to modify the clearance value of the cuff between its rear support position which provides the advance angle, and its abutment position in front support from which the front cuff provides the maximum stiffness.
Another known boot of this type, also with flexion control means of the upper with respect to force, position, and amplitude, is described in patent application DE 19 63 342. According to this document, the boot has a shell base which is provided along its sides with two vertical extensions on which are connected a front cuff and a rear spoiler, both journalled at their lower portion on the shell base.
These vertical extensions are each provided with a projecting lug which acts as an abutment for limiting frontward pivoting of the rear spoiler, and rearward pivoting of the front cuff, and possibly constitute flexion resistance means, which resistance can be modulated either by varying the friction conditions in the cuff overlapping zones on the extensions or by positioning intermediate elastic elements.
It is apparent from such a structure that the flexion amplitude of the upper cannot be controlled because it varies with the tightening positioning of the cuff and spoiler along the lower part of the skier's leg; indeed, when the cuff and spoiler are more or less close to one another, depending upon whether the lower part of the leg has a small or large perimeter, they come more or less close to the abutment lug, and therefore, their possibility of clearance is thereby more or less reduced.
Another disadvantage, related to the determination of the advance angle, results from the fact that the cuff and spoiler are reciprocally and individually adjustable by tightening along the lower part of the leg without reference abutment. Therefore, the front cuff and rear spoiler adopt the inclination imposed by the lower part of the skier's leg while putting on of the boot, and there is nothing to allow the skier to identically reproduce this inclination or advance angle in the other boot.